Does anyone else recall the regular experimental routing of scheduled passenger services up the East Coast from London on 1991/2? It was a sort of "hang a left at Clacton VOR and keep going north-ish"-arrangement . The idea was to free capacity on the Daventry Sector.
The Aerad charts were almost solid blue east of Alpha 1 in those days, service provided by Eastern Radar, and intercepts fairly common, so I understand.
Somewhere there is a photo of a couple of Tornadoes formate-ing with a BA 757.